So sorry to hear that Salamon. Any idea what caused the diarrhea? Don't lose faith. Things will get better. Unfortunately this is the way fissures can go...good days and bad days. I hope tomorrow is a better one for you.
As for the colonoscopy preparation. Yes, you will pee out of your butt many times, however, many on here have said it is not as bad as diarrhea because it doesn't burn. I did mine so long ago I can't comment on that. Good reason to put the test off for a bit though.